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Baszczyk, M.

Publications and source records attributed to Baszczyk, M..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Proton-proton interactions and onset of deconfinement

The experiment of the NA61/SHINE Collaboration at the CERN SPS is performing a unique study of the phase diagram of strongly interacting matter by varying collision energy and nuclear mass number of colliding nuclei. In central Pb + Pb collisions, the experiment of the NA49 Collaboration found structures in the energy dependence of several observables in the energy range of the CERN SPS that had been predicted for the transition to a deconfined phase. New measurements of the NA61/SHINE Collaboration find intriguing similarities in $p + p$ interactions for which no deconfinement transition is expected at the energies of the SPS. Possible implications will be discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Search for an exotic S = – 2 , Q = – 2 baryon resonance in proton-proton interactions at s N N = 17.3 GeV

Pentaquark states have been extensively investigated theoretically in the context of the constituent quark model. In this paper results of an experimental search for pentaquarks in the Ξ – π – , Ξ – π + , Ξ ¯ + π – and Ξ ¯ + π + invariant mass spectra in proton-proton interactions at s = 17.3 GeV are presented. Previous possible evidence from the NA49 collaboration of the existence of a narrow Ξ – π – baryon resonance in p + p interactions is not confirmed with almost 10 times greater event statistics. The search was performed using the NA61/SHINE detector which reuses the main components of the NA49 apparatus. No signal was observed with either the selection cuts of NA49 or newly optimized cuts.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Measurement of $\phi $ meson production in $p + p$ interactions at 40, 80 and $158 \, \hbox {GeV}/c$ with the NA61/SHINE spectrometer at the CERN SPS

Results on $\phi$ meson production in inelastic p+p collisions at CERN SPS energies are presented. They are derived from data collected by the NA61/SHINE fixed target experiment, by means of invariant mass spectra fits in the $\phi \to K^+K^-$ decay channel. They include the first ever measured double differential spectra of $\phi$ mesons as a function of rapidity $y$ and transverse momentum $p_T$ for proton beam momenta of 80 GeV/c and 158 GeV/c, as well as single differential spectra of $y$ or $p_T$ for beam momentum of 40 GeV/c. The corresponding total $\phi$ yields per inelastic p+p event are obtained. These results are compared with existing data on $\phi$ meson production in p+p collisions. The comparison shows consistency but superior accuracy of the present measurements. The emission of $\phi$ mesons in p+p reactions is confronted with that occurring in Pb+Pb collisions, and the experimental results are compared with model predictions. It appears that none of the considered models can properly describe all the experimental observables.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Measurements of $\pi ^\pm $, $K^\pm $ and proton double differential yields from the surface of the T2K replica target for incoming 31 GeV/c protons with the NA61/SHINE spectrometer at the CERN SPS: NA61/SHINE Collaboration

Measurements of the $\pi^{\pm}$, $K^{\pm}$, and proton double differential yields emitted from the surface of the 90-cm-long carbon target (T2K replica) were performed for the incoming 31 GeV/c protons with the NA61/SHINE spectrometer at the CERN SPS using data collected during 2010 run. The double differential $\pi^{\pm}$ yields were measured with increased precision compared to the previously published NA61/SHINE results, while the $K^{\pm}$ and proton yields were obtained for the first time. A strategy for dealing with the dependence of the results on the incoming proton beam profile is proposed. Furthermore, the purpose of these measurements is to reduce significantly the (anti)neutrino flux uncertainty in the T2K long-baseline neutrino experiment by constraining the production of (anti)neutrino ancestors coming from the T2K target.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of the shape of the Λ b 0 → Λ c + μ – ν ¯ μ differential decay rate

A measurement of the shape of the differential decay rate and the associated Isgur-Wise function for the decay Λ 0 b →Λ + c μ – ¯νμ is reported, using data corresponding to 3 fb –1 collected with the LHCb detector in proton-proton collisions. The Λ + c μ – ¯ν μ (+anything) final states are reconstructed through the detection of a muon and a Λ + c baryon decaying into pK – π + , and the decays Λ 0 b →Λ + c π + π – μ – ¯ν μ are used to determine contributions from Λ 0 b →Λ* c + μ – ¯νμ decays. The measured dependence of the differential decay rate upon the squared four-momentum transfer between the heavy baryons, q 2 , is compared with expectations from heavy-quark effective theory and from unquenched lattice QCD predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Updated search for long-lived particles decaying to jet pairs

A search is presented for long-lived particles with a mass between 25 and 50GeV/c 2 and a lifetime between 2 and 500 ps, using proton–proton collision data corresponding to an integrated luminosity of 2.0fb -1 , collected by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The particles are assumed to be pair-produced in the decay of a 125GeV/c 2 Standard-Model-like Higgs boson. The experimental signature is a single long-lived particle, identified by a displaced vertex with two associated jets. No excess above background is observed and limits are set on the production cross-section as a function of the mass and lifetime of the long-lived particle.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Improved limit on the branching fraction of the rare decay ${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$

A search for the decay ${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$ is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of 3fb -1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8TeV. The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of Β (${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$ ) < 0.8 (1.0) × 10 -9 at 90%(95%) confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Study of prompt $D^0$ meson production in $p$Pb collisions at $\sqrt{s_{\mathrm{N}\;\mathrm{N}}}=5$ TeV

Production of prompt $D^0$ mesons is studied in proton-lead and lead-proton collisions recorded at the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of 1.58±0.02 nb -1 recorded at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{NN}}$ = 5 TeV. Measurements of the differential cross-section, the forward-backward production ratio and the nuclear modification factor are reported using $D^0$ candidates with transverse momenta less than 10 GeV/ c and rapidities in the ranges 1.5 < y* < 4.0 and -5.0 < y* < -2.5 in the nucleon-nucleon centre-of-mass system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurements of $$\pi ^\pm $$ π ± , K $$^\pm $$ ± , p and $${\bar{\text {p}}}$$ p ¯ spectra in proton-proton interactions at 20, 31, 40, 80 and 158 $$\text{ GeV }/c$$ GeV / c with the NA61/SHINE spectrometer at the CERN SPS: The NA61/SHINE Collaboration

Measurements of inclusive spectra and mean multiplicities of $\pi^\pm$, K$^\pm$, p and $\bar{\textrm{p}}$ produced in inelastic p+p interactions at incident projectile momenta of 20, 31, 40, 80 and 158 GeV/c ($\sqrt{s} = $ 6.3, 7.7, 8.8, 12.3 and 17.3 GeV, respectively) were performed at the CERN Super Proton Synchrotron using the large acceptance NA61/SHINE hadron spectrometer. Spectra are presented as function of rapidity and transverse momentum and are compared to predictions of current models. The measurements serve as the baseline in the NA61/SHINE study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Observation of charmless baryonic decays B ( s ) 0 → p p ¯ h + h ' –

Decays of B 0 and B 0 s mesons to the charmless baryonic final states p¯ph + h' – , where h and h' each denote a kaon or a pion, are searched for using the LHCb detector. The analysis is based on a sample of proton-proton collision data collected at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb –1 . Four-body charmless baryonic B 0 s decays are observed for the first time. The decays B 0 s →p¯pK + K – , B 0 s →p¯pK ± π ∓ , B 0 →p¯pK ± π ∓ and B 0 →p¯pπ + π – are observed with a significance greater than 5 standard deviations; evidence at 4.1 standard deviations is found for the B 0 →p¯pK + K – decay and an upper limit is set on the branching fraction for B 0 s →p¯pπ + π – . Branching fractions in the kinematic region m(p¯p) < 2850 MeV/c 2 are measured relative to the B 0 →J/ψ(→p¯p)K*(892) 0 channel.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Prompt and nonprompt J / ψ production and nuclear modification in p Pb collisions at s N N = 8.16 TeV

The production of J/ψ mesons is studied in proton-lead collisions at the centre-of-mass energy per nucleon pair s N N = 8.16 TeV with the LHCb detector at the LHC. The double differential cross-sections of prompt and nonprompt J/ψ production are measured as a function of the J/ψ transverse momentum and rapidity in the nucleon–nucleon centre-of-mass frame. Forward-to-backward ratios and nuclear modification factors are determined. The results are compared with theoretical calculations based on collinear factorisation using nuclear parton distribution functions, on the colour glass condensate or on coherent energy loss models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of meson resonance production in $\pi ^- + C$ interactions at SPS energies: The NA61/SHINE Collaboration

Here, we present measurements of $\rho^0$, $\omega$ and K$^{*0}$ spectra in $\pi^{-} + $C production interactions at 158 GeV/c and $\rho^0$ spectra at 350 GeV/c using the NA61/SHINE spectrometer at the CERN SPS. Spectra are presented as a function of the Feynman's variable $x_\text{F}$ in the range $0 < x_\text{F} < 1$ and $0 < x_\text{F} < 0.5$ for 158 GeV/c and 350 GeV/c respectively. Furthermore, we show comparisons with previous measurements and predictions of several hadronic interaction models. Our measurements are essential for a better understanding of hadronic shower development and for improving the modeling of cosmic ray air showers.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Measurement of B 0 , B s 0 , B + and Λ b 0 production asymmetries in 7 and 8 TeV proton–proton collisions

The B 0 , B s 0 , B + and Λ b 0 hadron production asymmetries are measured using a data sample corresponding to an integrated luminosity of 3.0 fb –1 , collected by the LHCb experiment in proton–proton collisions at centre-of-mass energies of 7 and 8 TeV. The measurements are performed as a function of transverse momentum and rapidity of the b hadrons within the LHCb detector acceptance. The overall production asymmetries, integrated over transverse momentum and rapidity, are also determined.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Test of lepton universality with $B^0 → K^{*0} ℓ^+ ℓ^-$ decays

A test of lepton universality, performed by measuring the ratio of the branching fractions of the $B^0 → K^{*0}μ^+μ^-$ and $B^0$ → $K^{*0}e^+e^-$ decays, $R_{K^{*0}}$, is presented. The $K^{*0}$ meson is reconstructed in the final state $K^+π^-$, which is required to have an invariant mass within 100 MeV/ c 2 of the known $K^*$ (892) 0 mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb -1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q 2 , to be R K &#x2217;<!-- * --> 0 = { 0.66 &#x2212;<!-- - --> + 0.07 0.11 ( s t a t ) &#x00B1;<!-- ± --> 0.03 ( s y s t ) f o r 0.045 < q 2 < 1.1 G e V 2 / c 4 , 0.69 &#x2212;<!-- - --> + 0.07 0.11 ( s t a t ) &#x00B1;<!-- ± --> 0.05 ( s y s t ) f o r 1.1 < q 2 < 6.0 G e V 2 / c 4 . The corresponding 95.4% confidence level intervals are [0.52, 0.89] and [0.53, 0.94]. The results, which represent the most precise measurements of $R_{K^{*0}}$ to date, are compatible with the Standard Model expectations at the level of 2.1–2.3 and 2.4–2.5 standard deviations in the two q 2 regions, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Resonances and $CP$ violation in $B_s^0$ and ${\overline{B}}_s^0\to J/\psi {K}^{+}{K}^{-}$ decays in the mass region above the $Φ(1020)$

The decays of $B_s^0$ and ${\overline{B}}_s^0$ mesons into the $J/ψK^+K^-$ final state are studied in the $K^+K^-$ mass region above the $Φ(1020)$ meson in order to determine the resonant substructure and measure the $CP$-violating phase, $Φ_s$, the decay width, $Γ_s$, and the width difference between light and heavy mass eigenstates, $ΔΓ_s$. A decay-time dependent amplitude analysis is employed. The data sample corresponds to an integrated luminosity of 3 fb -1 produced in 7 and 8 TeV pp collisions at the LHC, collected by the LHCb experiment. The measurement determines $Φ_s$ = 119 ± 107 ± 34 mrad. A combination with previous LHCb measurements using similar decays into the $J/ψπ^+π^-$ and $J/ψΦ(1020)$ final states gives $Φ_s$ = 1 ± 37 mrad, consistent with the Standard Model prediction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗